1. Field of the Invention
The present invention relates generally to the art of detecting load current, and more particularly, to a real-time load current detecting circuit for a central processing unit (CPU).
2. Description of the Related Art
According to the prior art, a conventional power supply system having a load current detecting device for detecting load current includes a conventional load current detecting circuit 60. Referring to FIG. 2, the detecting circuit 60 technically employs a power supply 61 to provide direct current (DC) of low voltage level and provide a CPU 69 or other load devices with required electricity for operation. Further, a stored-energy inductor L6 and a stored-energy capacitor C6 are employed in cooperation with a pulse width modulation (PWM) controller 62 to control high-gate and low-gate control signals for respective controls of ON and OFF of the two switches 64, thus enabling the power supply 41 to provide the required electricity for the CPU 69. Furthermore, a resistor 66 and a conductor 67 are employed for monitoring the surface temperature of the CPU 69; specifically, it primarily employs the inductor 67 to detect the voltage drop of the resistor 66 to indirectly detect the amperage of and the variation of the voltage drop of the CPU 69.
However, the above-mentioned detecting circuit had greater inaccuracy because of employing the resistor 66 for detection or measurement of variation of the current. The solution to such drawback, i.e. control of rotational speed of the cooling fan of the CPU, fails to definitely improve it.
The above-mentioned invention was to improve the aforementioned drawback, having a current load detecting circuit 70 in addition to the conventional detecting circuit 60, as shown in FIG. 3. In light of this, the high-gate and low-gate control signals or the variation of duration of high/low levels of PWM signals can be detected to enable real-time countermeasure, i.e. the cooling fan of the CPU is controlled to run faster to enhance the heat-dissipating efficiency, to improve the drawback.
Although the aforementioned invention can monitor/detect the current, the actual detection of the current is done by the variation of the current measured by the combination of the high-gate and low-gate control signals and the PWM signals. Thus, there is still inaccuracy.